title: Development of a model of elevated intraocular pressure in rats by gene transfer of bone morphogenetic protein 2.
abstract: OBJECTIVE
  To determine whether inducing calcification in the trabecular meshwork results in elevated IOP in living rats. To use this property to create an elevated IOP animal model by gene transfer of bone morphogenetic protein 2 (BMP2).
  
  
  METHODS
  Calcification was assessed by alizarin red staining in primary human trabecular meshwork (HTM) cells and alkaline phosphatase (ALP) activity in the angle tissue. Brown Norway (BN) and Wistar rats were intracamerally injected with Ad5BMP2 (OS) and control Ad5.CMV-Null (OD). IOPs were taken twice a week and expressed as mean integral pressures. Morphology was assessed on fixed, paraffin-embedded anterior segments. Retinal ganglion cells (RGCs) were quantified on retrograde and Brn-3a-labeled flat mounts using MetaMorph software.
  
  
  RESULTS
  BMP2-treated cells displayed marked increase in calcification. Trabecular meshwork tissue showed moderate ALP activity at 13 days postinjection. Fifty-four of 55 BN and 15 of 19 Wistar rats displayed significantly elevated IOP. In a representative 29-day experiment, the integral IOP difference between treated and control eyes was 367.7 ± 83 mm Hg-days (P = 0.007). Morphological evaluation revealed a well-organized trabecular meshwork tissue, exhibiting denser matrix in the treated eyes. The Ad5BMP2-treated eye showed 34.4% ± 4.8% (P = 0.00002) loss of peripheral RGC over controls.
  
  
  CONCLUSIONS
  Gene transfer of the calcification inducer BMP2 gene to the trabecular meshwork induces elevated IOP in living rats without altering the basic structure of the tissue. This strategy generates an elevated IOP model in rats that would be useful for evaluation of glaucoma drugs targeting the outflow pathway.
authors.affiliation: Department of Ophthalmology, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599-7041, USA.
authors.forename: Lakisha K
authors.initials: LK
authors.lastname: Buie
authors.forename: Md Zahidul
authors.initials: MZ
authors.lastname: Karim
authors.forename: Matthew H
authors.initials: MH
authors.lastname: Smith
authors.forename: Teresa
authors.initials: T
authors.lastname: Borrás
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D055396:Bone Morphogenetic Protein 2 / Q000008:administration & dosage / Q000096:biosynthesis / Q000235:genetics*; D002114:Calcinosis / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D002478:Cells, Cultured; D004195:Disease Models, Animal; D005786:Gene Expression Regulation; D018014:Gene Transfer Techniques; D006801:Humans; D007150:Immunohistochemistry; D007429:Intraocular Pressure / Q000502:physiology*; D008297:Male; D009798:Ocular Hypertension / Q000235:genetics* / Q000378:metabolism / Q000503:physiopathology; D012313:RNA / Q000235:genetics*; D051381:Rats; D011914:Rats, Inbred BN; D017208:Rats, Wistar; D060888:Real-Time Polymerase Chain Reaction; D014129:Trabecular Meshwork / Q000187:drug effects / Q000473:pathology*; D055815:Young Adult
chemical_list: D055396:Bone Morphogenetic Protein 2; D012313:RNA
keywords: adenoviral gene transfer; elevated IOP model; rat; trabecular meshwork